Inshore Palm Islands

The northern boundary of the Palm Island Inshore reporting zone extends east from the north-west bank of the Seaforth Channel mouth, just south of Hinchinbrook Island, to the offshore boundary and includes enclosed coastal, open coastal and mid-shelf waters.

The southern boundary of the Palm Island zone extends eastward from the southern boundary of the Herbert River Basin to just east of the Palm Island Group and runs north to the Wet Tropics NRM marine region boundary at the junction with the offshore waters boundary.

The major river discharging into the Palm Island zone is the Herbert River. Several sub-catchments, including the Seymour River, also discharge into the Palm Island inshore zone.

Water quality in the Palm Island zone is affected by plumes of sediments, nutrients and pesticides from rivers discharging directly into the zone but also from the plumes of southern rivers, particularly the Burdekin River the mouth of which is approximately 180 km to the south-east.

The area includes the Palm Island group located approximately 17 km east of the mainland. The Palm Island Group includes Orpheus Island, Pelorus Island, Fantome Island, Palm Island, and Havannah Island. These islands provide fringing shallow water environments that support coral reef ecosystems and reef seagrass meadows.

The overall grade for Palm Island zone remained ‘moderate’ with the score increasing from 51 in 2017-18 to 56.

The diagram below shows the detailed results for each indicator by year. Click on the timeslider to see data from previous years.

Water quality

The water quality grade in 2018-19 for the Palm Island inshore zone remained ‘moderate’ and the score increased from 53 in 2017-18 to 60.

Water quality grades are based on water quality guideline trigger values established for the waters of the Great Barrier Reef Marine Park that, if exceeded, identify the need for management responses. The guidelines are not targets or assessments of pollutant loads entering the marine environment. The results are derived from in-situ water samples and water quality loggers at two inshore locations and passive pesticide samplers located Lucinda jetty.

The water clarity score of 80 (‘good’) is comprised of total suspended solids (‘very good’) and turbidity (‘good’).

Nutrients scored 2 (‘very poor’) and declined from a grade of moderate in 2017-18. Nutrients are comprised of oxidised nitrogen (NOx), particulate nitrogen (PN) and particulate phosphorus (PP) and all three indicators graded ‘very poor’. Concentrations of all three nutrient indicators were highest during and following periods of high rainfall and river discharges between December and February.

The chlorophyll a score in the Palm Island zone was 66 (‘good’) and increased substantially from 46 (‘moderate’) the previous year.

Using the pesticide risk metric pesticides were graded “very good” and scored 91, equating to greater than 99 percent of species protected.

 

Coral

The overall coral grade in 2018-19 for the Palm Island inshore zone was 52 (‘moderate’). The coral index in the Palm Island zone has remained a ‘moderate’ grade since 2014-15.

The coral grade is comprised of the density of juvenile hard corals score of 45 (‘moderate’), the macroalgae cover score of 45 (‘moderate’), the coral cover score of 44 (‘moderate’), the change in coral cover score of 61 (‘good’), and the coral community composition score of 67 (‘good’).

The coral condition score increased slightly for the Palm Island zone and was driven by increases for the macroalgae cover, coral cover, juvenile density and species composition indicators, however the coral cover change indicator decreased. At some shallow Palm Island sites there was high cover of macroalgae and low juvenile densities, both of which limit the scores of these indicators for the zone.

More information on recent changes in coral indicators and the relationships with environmental conditions are provided in the latest Marine Monitoring Program inshore coral report (Thompson et al. 2020).

 

Seagrass

There is no current seagrass monitoring undertaken in the Palm Island Zone and consequently there is no seagrass grade available for the Report Card in the Palm Island Zone. 

 

Fish

The fish index is currently under development and will be available in future report cards.

 

References

Thompson A, Costello P, Davidson J, Logan M, Greg Coleman (2019) Marine Monitoring Program. Annual Report for inshore coral reef monitoring: 2017 to 2018. Australian Institute of Marine Science, Townsville.132 pp. 

 

See the detailed reports for further information on the methods used to produce the scores and grades and the detailed results